The handling of articles frequently involves grouping individual articles or several articles simultaneously into article layers, for instance, such that the article layers can later be stacked in a stacking station to form a stack, for instance, in which stack the article layers then form stack layers.
The articles can be, for instance, objects such as packaged or unpackaged objects, containers, cartons, or they can be bundles of a plurality of objects, with the objects of a bundle being held together, for instance, by means of a strapping, an outer packaging, such as a wrapping, a shrink tube, or a box, or a carrying structure, to mention just a few conceivable embodiments.
The grouping of articles into article layers, for instance, is carried out particularly effectively by means of so-called grouping stations, which can be operated fully automatic. Grouping stations can comprise one or a plurality of rotating stations, track switches, and/or also single- or multi-axle handling machines summed up under the term manipulator, which continually group articles on a staging surface from a single- or multi-lane incoming article flow into article layers, which are thereupon transported away after their completion in order to make space for a new article layer to be grouped.
In the process, the articles are detected by sensor with regard to their alignment and/or position in the single- or multi-lane incoming article flow in order to be able to subsequently manipulate them in correspondence to their grouping in the article layer to be achieved by means of one or a plurality of manipulators. Grouping stations are normally clock-controlled and they perform a sequence of steps defined for the articles to be presently grouped, independent of whether one or a plurality of articles in a grouping having been formed up to that point for attaining a desired article layer is or are in the correct arrangement or alignment and/or in the correct position or place that is necessary for the desired article layer to be achieved. The articles in the grouping having been formed by the manipulation up to that point are therefore also detected by sensor in order to recognize mispositioned or fallen articles. For this purpose, a plurality of light barriers is located in the area of the staging surface of a grouping station, which light barriers monitor the articles having been grouped up to that point and stop the grouping station if one or a plurality of articles is in a wrong position or in a wrong alignment.
Since mispositioned or fallen articles can lead to collisions with new incoming articles to be grouped if the grouping station continues to be operated, and, as a result, can in the best case lead to damaging the collided articles and in the worst case to damaging the grouping station or parts of it, grouping stations are shut down with a disruption message being issued if mispositioned or fallen articles in a grouping having been formed up to that point are detected by sensor.
The staging surface is emptied in order to remove the disruption. The grouping station thereupon takes up grouping a new article layer again by carrying out the first step of the sequence of steps.
Although for the most part flawless, the articles that were cleared out are treated as rejects, as they can only be reintegrated into the single- or multi-lane incoming article flow with substantial effort.
Besides the undesirably high number of rejects, the grouping station downtime necessary for completely emptying the staging surface and thus for the most part also the downtime of a complete production line preceding the grouping station, such as a filling line, for instance, is a substantial disadvantage of the known grouping stations. Emptying is particularly impeded by necessary occupational safety measures, which require the staging surface to be encapsulated at least during the operation of the grouping station, so that it takes up a similar amount of time to empty the staging surface as it would to empty a room that is difficult to access.
Mathematical detection of the spatial arrangement of objects on an infeed conveying device, alignment of the objects in a predefined manner by means of handling machines that are freely programmable in three axes, and evenly spaced transfer of the objects onto a further conveyor device for the purpose of placing the objects in a packaging unit are known from DE 37 04 423 A1. The further conveyor device feeds the objects to an insertion area, where the positioned insertion of the objects into the packaging unit is performed by means of inserting heads. The handling machines are controlled by a computer, which receives the position data and the arrangement data of the objects on the infeed conveying device from an optical detection system.
Determining the alignment of an object with flexible walls and changing it, if necessary, by means of a manipulator, are known from DE 600 34 527 T2. In that instance, the alignment is detected by means of a pattern detector, which detects a pattern on a surface of the object, and is identified by means of a processor, which compares the detected pattern with a respective number of predefined patterns representing respective alignments of the object.
From DE 10 2007 036 020 A1, the unified alignment of a stream of differently aligned, separate objects being transported within a specified angle area in differing alignment on a supply transport device is known to be effected by means of an interposed alignment transport device forming a stream of objects in equal alignment being transported away on a removal transport device. For that purpose, the separate objects being transported on the supply transport device are first detected with regard to their alignment by means of an image recording device or a camera system. Then one object after the other is transferred to the alignment transport device according to their separation on the supply transport device, which undergoes a rotation about a vertical axis in dependence on the alignment detected by means of the image recording device or of a camera system of the object respectively located on it, such that the objects are equally aligned and fed to the removal transport device one after the other.
Detection by means of an image recording device of articles being transported in an article stream by means of a conveyor device is known from EP 2 500 147 A2.
In that context, the image recording device first detects the entire length of the conveyor device. For the purpose of adapting the detection of individual articles in the article stream to differently dimensioned articles, a display is provided for presenting the image detected by the image recording device. Based on the size of a section of the detected image and by means of a user interface, it is possible to configure an area as a start condition for the detection of an article within which section an article to be detected is located. The size of this section corresponding to the dimensions of the article is determined by the relation of the area to the total length of the conveyor device.